Test Subject is one of the three final bosses of Slay the Spire 2 that you may face at the end of Act 3. For many, it is also the most difficult due to all the phase gimmicks.
Lucky for you, we have prepared this Test Subject boss guide to help you consistently beat all of its phases.
Table of Contents
Attack Pattern
Test Subject C10 is a multi-phase boss, with each phase having its own gimmick.
Phase 1
During the first phase, Test Subject has Enrage, which makes it so that each time you play a Skill card, the boss will gain 2 Strength.
It starts off with 20 attack damage, so unless you have a card that grants a lot of block at low cost, it’s best to tank the hit and deal a lot of your own damage.
The ideal strategy for this phase is to equip yourself with the Block Potion and Fortifier, then focus on offense. Using block cards is not always the best because they increase the boss’s Strength.
Since Test Subject only has 100 HP, it is easy to tank/potion the first hit and defeat it before it hits you the second time.
Phase 2
In the second phase, the Test Subject has Painful Stabs. So, each time you receive unblocked damage, a Wound card is shuffled into your discard pile.
Reliable block generation will be key for this phase. Unlike earlier, receiving even 1 unblocked damage can mess with your card draws. So you either go full defense or none at all.
Test Subject’s damage output is still brutal in this phase, going as high as 30. You need to take out its 200 HP before it eats away at your cards.
Phase 3
For the third phase, Test Subject gives itself Nemesis, which makes it Intangible every other turn, starting with the first. Despite its high HP, the third phase is more straightforward than the rest.
During the turns when it is intangible, you focus on blocking and applying debuffs to set up for your attacks. If you have sufficient health, we suggest tanking the hits of the second and fourth turns.
Still, Test Subject will hit like a truck, with some turns having over 40 damage. You can reduce its damage output with cards that apply Weak and Vulnerable, and keep yourself on the safe side.
The Boss Is Supposed to Be Tough
Test Subject C10 is intended to be very difficult. Still, considering the game has just entered early access, it could be nerfed in the future. Until then, we have to beat it the good old way.
Once you have defeated the Test Subject, your run will be concluded, and you will meet a certain someone at the top. There’s no fight after Act 3, so use all your resources on Test Subject.